1. Field of the Invention
This invention relates to a bio-adhesive composition and more specifically, this invention relates to a phosphate-based adhesive for bone, ligament and tendon repair and stabilization, and a method for applying the composition during surgery.
2. Background of the Invention
The use of synthetic materials to expedite healing is becoming more widespread. A burgeoning area of growth is the use of relatively inert hardening agents for use as bone substitute materials. In such uses, surgeons apply the substitute material to fractures. In situ hardening of the material occurs either during surgery, or after suturing.
Synthetic hardening agents include polymethylmethacrylate and other similar polymers. Alternatively, a myriad of calcium-containing substances are utilized as bone substitutes. For example, U.S. Pat. No. 5,605,713 issued to Boltong on Feb. 25, 1997, and U.S. Pat. No. 5,152,836 issued to Hirano on Oct. 6, 1992 discloses the use of calcium orthophosphate cements as a bone substitute.
However, these and other disclosures appear to provide a material merely for filling bone defects. None of the currently available materials provide both an adhesive filler and a bio-adhesive, to both fill voids and fractures and also provide structural support to the bone, and adjacent structures such as ligaments and tendons. Also, some of these compounds have high molar ratios of Ca to P, and therefore tend to remain in the body and are not resorbed.
None of the known biocomposites or biopolymers provide a means for enhancing adhesion to bone and existing structures aside from the chemical adhering aspects of the mixture. As such, fasteners (such as screws or clamps) often are utilized to hold the physiological structures until the mixtures can cure. Often these fasteners are not biodegradable.
A need exists in the art for a reabsorbable bio-adhesive. The adhesive should incorporate typical calcium-containing moieties to minimize its cost. The adhesive should maintain its workability and ultimately xe2x80x9csetxe2x80x9d under physiologic conditions, including temperature, pH and humidity. The material should be absorbed by the body without any untoward side effects. Also, the adhesive should be applicable to bone, ligaments and tendons so as to provide both void-filling and fracture repair capabilities and structural support. Finally, the bioadhesive should confer means to both chemically and mechanically fasten structures in place in vivo.
An object of the present invention is to provide a substance and a method for a bio-adhesive that overcomes many of the disadvantages of the prior art.
Another object of the present invention is to provide a bio-adhesive to effect the in-situ repair and adherence of body parts to each other and to adjacent structures. A feature of the invention is that the adhesive xe2x80x9csetsxe2x80x9d at physiologic temperatures, and pH and within approximately 10 and 15 minutes. Another feature of the invention is that the bio-adhesive expands in vivo. An advantage of the invented formulation is its ability to simultaneously fill bone defects and provide structural support. Another advantage is that the expandability of the adhesive during setting or curing confers additional mechanical contact between the adhesive and body parts and between body parts and such adjacent structures as manmade materials and biological materials.
Yet another object of the present invention is to provide a bone substitute and a platform for bone formation. A feature of the invention is the utilization of CaSiO3 or Ca10(PO4)6(OH)2 in combination with MgO and magnesium potassium phosphate to prepare the material. An advantage of the substance is its gradual absorption by the body without rejection or reaction to contacted structures.
Briefly, the invention provides a bio-adhesive comprising a means for attaching objects to bone; a means for enhancing said attachment means; and a means for facilitating in vivo degradation of the bio-adhesive. The bioadhesive is derived from a mixture comprising KH2PO4, a metal oxide, a calcium-containing compound, and water. One such compound is tricalcium phosphate.
Also provided is a method for fastening structures to bone surface, in vivo, the method comprising accessing the bone surface through a surgically-induced incision; simultaneously applying a phosphate-containing bio-adhesive to the structures and to the bone surface; closing the incision; and allowing the adhesive to expand.